expected initializer before ‘*’ token

Question

I am trying to implement the code in the Design Patterns book. I am getting the following error:

expected initializer before ‘*’ token

for this line:

static Singleton *Singleton::itsInstance = 0;

Here's the complete code. I am using g++ 4.2.1 to try and compile this.

class Singleton {
public:
    static Singleton *instance();
protected:
    Singleton();
private:
    static Singleton *itsInstance;
}

static Singleton *Singleton::itsInstance = 0;

Singleton *Singleton::instance()
{
    if (!itsInstance)
    {
        itsInstance = new Singleton;
    }
    return itsInstance;
}

Any ideas?

You're missing a semicolon after the class definition. Also you don't need the word `static` before the definition. — Seth Carnegie, Feb 06 '13 at 04:08
Seth is right. But while we're piling on - you should probably cast `0` to a pointer before assigning it. — Brian Cain, Feb 06 '13 at 04:10
@BrianCain No casting needed when assigning from `NULL`, `0` or `nullptr`. — Some programmer dude, Feb 06 '13 at 04:11
Remove "static" from the definition (below the class). It's illegal. And the missing semicolon at the end of the class declaration, already pointed out. — doug65536, Feb 06 '13 at 04:12
You may want to check: http://stackoverflow.com/a/1008289/14065 — Martin York, Feb 06 '13 at 06:16

score 17 · Accepted Answer · answered Feb 06 '13 at 04:09

17

class Singleton {

};
 ^^^

This! and also,

static Singleton *Singleton::itsInstance = 0;

replaced with:

Singleton *Singleton::itsInstance = 0;

You need the static only on the declaration not on the definition.

answered Feb 06 '13 at 04:09

Alok Save

202,538
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Aaargh! Thanks, that was it. – Stephen Rasku Feb 06 '13 at 04:10

score 1 · Answer 2 · answered Feb 06 '13 at 04:11

1

You are missing a semicolon after your class definition, and you do not want the static.

static Singleton *Singleton::itsInstance = 0;

should be

Singleton *Singleton::itsInstance = 0;

answered Feb 06 '13 at 04:11

EClaesson

1,568
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expected initializer before ‘*’ token

2 Answers2